Data storage systems are used to store large amounts of information received from one or more sources. A data storage system often comprises a storage controller in communication with one or more clients, often referred to as “hosts,” and also in communication with a plurality of data storage devices. A host computing device may send a storage controller a write command to write certain information to a data storage medium, and/or a read command to read information from a data storage medium, and/or a copy command to copy information from one data storage medium to another data storage medium. Host computers may also provide commands to a storage controller to establish or revise physical and/or logical configurations. In certain embodiments, a read command, or a write command, or a copy command, or a configuration command comprises a plurality of objects packaged in one command
Many storage systems include a number of different storage devices, each arranged in a number of tiers. The storage devices and associated tiers are arranged to provide different performance characteristics. For example, a high performance tier of a particular storage system may include a number of solid state disks (SSDs) that provide short seek times. Because SSDs can be relatively expensive, the storage system may also include a lower performance tier made up of a number of slower devices, such as Serial Advanced Technology Attachment (SATA) drives. Although the SATA drives provide higher seek times, they can be a more inexpensive way to store data than additional SSD drives.
In some implementations, the physical storage resources available to a particular storage system can be distributed as part of an environment in which client devices are allocated a certain number of virtual resources. Those virtual resources are then mapped to a physical resource. Virtualization technology provides the appearance of more physical resources (e.g., storage devices) than are actually available to the client.